Known shock absorber installations have a similar motion ratio for both roll and vertical wheel movements. Typically, these installations include at least one shock absorber having one end attached to the chassis of the vehicle and the other end attached to the axle of the vehicle.
Examples of known shock absorber installations can be found in for example, U.S. Pat. No. 2,941,817 which provides for a vehicle axle and air suspension assembly. A first end of a shock absorber is attached to an inside portion of a chassis. The second end of the shock absorber is attached to an inside portion of a non-steerable axle.
U.S. Pat. No. 4,262,929 teaches a vehicle suspension for connecting an axle to the frame. The suspension includes both a spring and a shock absorber. The upper end of the shock absorber is mounted to a vehicle frame beam. The lower end of the shock absorber is mounted to the axle.
U.S. Pat. No. 4,802,690 provides for a suspension assembly for a steering axle. The assembly uses a shock absorber attached to both the chassis side rail and a portion of the axle adjacent the air spring.
U.S. Pat. No. 6,073,946 teaches a suspension system for a steerable axle assembly. The system has a shock absorber attached at a first end to the frame of the vehicle and a second end to a plate. The plate is attached to the axle of the vehicle.
U.S. Pat. No. 6,135,470 provides for a wheel axle suspension system having a shock absorber. The shock absorber is attached to the chassis frame member and to an axle seat directly above the axle.
The transient roll dampening characteristics of these known installations need to be improved while not exhibiting overly harsh vertical wheel movements. It has been found in the present invention that by locating at least one dampening structure having an inboard end pivotally mounted to a vehicle frame and an outboard end pivotally mounted to a king pin, that the transient roll dampening characteristics are improved.